Sony makes triple-wavelength laser source

[zombie]

25 May 2004

Engineers at Sony have made an optical head that is compatible with Blu-ray, DVD and CD recording media.

Sony has developed a three-wavelength optical source that could drive the convergence of three different recording media formats.

Capable of playing and recording Blu-ray discs, as well as conventional DVD and CD media, the optical head prototype features lasers emitting at 405nm, 660nm and 785nm in a single package.

The three laser emissions are dealt with by a single optical system featuring two separate optoelectronic integrated circuits (OEICs), one for the Blu-ray format and a second that handles both CD and DVD wavelengths.

The more complex optical design means that 20 parts are used in the prototype head, compared with just seven for a standard DVD/CD. However, Sony’s stand-alone Blu-ray head requires 19 parts even without the CD/DVD capability.

The prototype optical head measures 82x50x32 mm, similar to that of Sony’s existing Blu-ray product. Conventional DVD/CD heads are about half this size.

Although Sony’s laser chip package is said to be a “single unit”, it actually features two separate chips. In the company’s schematic representation, a chip containing the GaAs-based red and near-infrared sources sits on top of the GaN-based device required for blue-violet emission.

According to the company, the three sources will not emit light simultaneously, meaning that the three individual media types could not all operate at the same time.

Sony says that it is targeting commercialization of the three-wavelength head within two years. It plans to reduce the number of parts used and improve reliability.

From: http://www.compoundsemiconductor.net.../news/8/5/21/1